This invention is directed to a fuel injector and a method for controlling the flow of fuel.
It is known to provide a conventional fuel injector with a check valve to prevent the back flow of fuel at the end of each injection event. However, the abrupt fuel flow termination causes wear on the valve member due to the rapid movement of the valve member against its seat. This rapid movement is believed to trap a volume of fuel in the injection nozzle, causing the nozzle to stay open. This movement is believed to slow down the closing rate of the nozzle while permitting entry of combustion gases. As a result, both the check valve and the nozzle are believed to wear out prematurely in the conventional fuel injector.
Thus, there is a strong need to overcome these and other problems associated with the conventional fuel injector.
Accordingly, the present invention is directed to controlling fuel flow in a fuel injector, and to overcoming the disadvantages of the conventional art.
The present invention provides an injector for metering fuel into a combustion chamber. The injector comprises a body having a first portion and a second portion, a fuel passage extending through the body, and a closure member movably in the fuel passage between a first position and a second position, the fuel passage having a first segment extending through the first portion and a second segment extending through the second portion. The first position of the closure member permits fuel flow in a first direction through the fuel passage and the second position prohibits fuel flow in a second direction opposite to the first direction. The closure member permits a predetermined volume of fuel flow in the second direction before the closure member moves to the second position. A needle assembly is movable between a first position and a second position, the predetermined volume of fuel being related to the displacement of the needle assembly between the first position and the second position of the needle assembly.
The present invention further provides a method to control fuel flow through a fuel injector in an internal combustion engine. The method comprises providing a body, providing a closure member movable in the fuel passage between a first position and a second position, permitting fuel flow in a first direction through the fuel passage when the closure member is in the first position, prohibiting fuel flow in a second direction opposite to the first direction when the closure member is in the second position, and permitting a predetermined volume of fuel flow in the second direction before the movement of the closure member to the second position. The body includes a fuel passage extending through the body, the fuel passage having a first segment extending through the first portion and a second segment extending through the second portion.